In general, the demand for smaller, yet more powerful, electronic circuit modules, which have more features or capabilities and greater component density than their predecessors, has been increasing. This is especially true in the case of power converters that are often employed in power supplies. A power converter is a power processing circuit that converts an input voltage waveform into a specified output voltage waveform. In many applications requiring a DC output, switched-mode DC/DC power converters are frequently employed to advantage wherein both high conversion density and converter efficiency are key design requirements.
These switched-mode DC/DC power converters generally include, among other components, an inverter, an isolation transformer, and a rectifier on a secondary side of the isolation transformer. The inverter typically includes a main power switch that employs metal oxide semiconductor field effect transistors (MOSFETs) to convert a DC input voltage to an AC voltage. Then, the isolation transformer transforms the input AC voltage to an output AC voltage and the rectifier generates the desired DC voltage at the output of the power converter. The main power switch and rectifier switches are usually operated at relatively high switching frequencies. This allows the use of smaller components, such as inductors and capacitors, within the power converter.
In these devices, electrical connections between the various layers and components are typically accomplished with the use of vias, which, as well known, are openings or holes that extend through the board and that are typically have a conductive material, such as solder, therein. In some cases, they are also used to mechanically attach an electrical component, such as a transformer, to a PWB. Presently in technologies that implement core-on-board transformer technologies, vias are used to make connections to field effect transistors (FETs) and other components and drop into the board and then to the windings of the transformer and then back out.
Unfortunately, however, these vias consume valuable board space. When the board layout is complex and includes many electrical components, the number o vias (and the concomitant amount of board space consumed by them) increase dramatically. Such space requirements are necessary because no other components should overlay the via, and preferably, they should not be too close to the via. When a larger number of vias are required for the board layout, it becomes very difficult for manufacturers to keep the board dimensions and layout within specified design requirements and yet still make the number of electrical connections that are required for the desired operation of the device. In addition, the typical via is a through-hole via, and since it goes through all layers, routing of conductive traces on internal layers becomes an issue. Moreover, the electronics industry is quickly moving to on-board technology where more, if not all, of the components are formed directly on or within the board itself. This advancement in technology reduces the number of separate components that are soldered directly to the board. Thus, it is becoming ever more imperative that all space of the board is efficiently utilized.
Accordingly, what is needed is an electronic board with an interconnect system that over comes the disadvantages associated with via interconnects of the prior art PWBs.